1. Field of the Invention
The invention relates to a vehicle surrounding monitoring system and a vehicle surrounding monitoring method, in which the image of an area surrounding a vehicle is displayed.
2. Description of the Related Art
Japanese Patent Application Publication No. 2003-191810 (JP-A-2003-191810) describes a vehicle surrounding monitoring system that includes image-capturing means, bird's eye-image transformation means, and display means. The image-capturing means is provided in the rear portion of a vehicle. The bird's eye-image transformation means transforms the image of an area behind the vehicle that is captured by the image-capturing means into a bird's eye image. The bird's eye image, into which the image is transformed by the bird's eye-image transformation means, is displayed on the display means. The vehicle surrounding monitoring system further includes synthesized bird's eye-image generation means, and display control means. The synthesized bird's eye-image generation means generates a synthesized bird's eye image by combining a previous bird's eye image with a current bird's eye image. The display control means displays the synthesized bird's eye image generated by the synthesized bird's eye-image generation means, along with a vehicle figure on the display means to show the relation between the position of the vehicle and the area indicated by the synthesized bird's eye image.
In the above-described system, the synthesized image for display is generated using the previous image that is previously captured. With this configuration, because the previous image is used, the situation out of the field of view of the image-capturing means can also be displayed using the previous image. Accordingly, much information can be provided to a user, as compared to the configuration in which only the current image is displayed.
However, because the situation may change during the period from the time point when the previous image is captured until the current time point, the reliability of the information provided by the previous image is lower than the reliability of the information provided by the current image. Therefore, in the above-described technology, the previous image is covered with a gray filter to make it possible to distinguish the current image from the previous image. However, the user cannot determine the degree of decrease in the reliability of the previous image. That is, in the configuration in which the previous images are displayed in a uniform manner, the user cannot determine the difference in the reliability among the previous images.